34 
DR. PETTIGREW ON THE MUSCULAR ARRANGEMENTS 
slightest pressure, and resembles in some respects ,that found at the mouths of sinuses 
and in the smaller veins*. 
The ureters enter the bladder obliquely in a twofold sense, viz., from above downwards, 
and from without inwards with regard to the posterior mesial line, and from above down- 
wards and from without inwards with regard to the walls of the bladder itself. The degree 
of obliquity varies according to the degree of distention. In the flaccid or undistended 
bladder the ureters are directed towards each other at a considerable angle (Plate IV. 
fig. 14, 2 , 2 ), and the extent of wall traversed by them from the time they enter the 
bladder until they reach its interior, equals, as nearly as may be, half an inch. In the 
distended state, on the other hand, the ureters come together in a nearly straight line 
(Plate IV. fig. 18, 2 , 2 ), and the extent of wall traversed is increased to three-fourths of 
an inch, or thereabouts. The openings of the ureters in the flaccid bladder are 
separated by an interval, which varies in different bladders, and in the same bladders 
according to the degree of distension. Usually it is about an inch and a quarter in the 
flaccid bladder, and from an inch and a half to two inches in the distended one, 
Although the openings of the ureters are thus widely apart, it does not follow that the 
ureters, or rather the muscular fibres composing them, terminate where the openings 
occur. On the contrary, the muscular fibres of the ureters are continued between the 
uretral openings, and are as strongly pronounced in the interior of the bladder as they 
are on the exterior and within the walls. There is in fact no breach of continuity 
in the muscular fibres of the ureters within the bladder, and the two ureters unite 
in the mesial line to form a strong loop or girder in which the viscus may be said to be 
suspended or slung. This arrangement prevents puckering of the coats of the bladder 
at the points where the ureters open, and secures to those portions of the ureters 
imbedded in the walls of the bladder a relative and definite position. The continuity 
referred to is best seen when the preparation is rendered transparent and held against 
the light. When so viewed the ureters (continued into each other) appear as a strong 
dark band, which is as distinctly pronounced between the orifices of the ureters as 
within the walls of the bladder itself (Plate IV. figs. 14, 17, & 18, 2 , 2 '; Plate V. dia- 
gram 7, v z). In addition to being continuous with each other, the fibres of the ureters, 
as was satisfactorily shown by Hodgson j" and Ellis J, are continuous with those of the 
neck of the bladder and the urethra. The fibres which connect the ureters with those 
investing the urethral canal, converge in a downward direction, those which are 
nearest the median line (Plate V. diagram 7 , a a!) coming together and crossing at very 
acute angles ( c c), those which are deeper coming together and crossing at wider angles 
(g g), the deepest having a nearly transverse direction, as in the so-called central layer 
* Vide paper by the Author “ On the Relations, Structure, and Functions of the Valves of the Vascular 
System in Vertebrata,” Trans. Roy. Soc. Edin. vol. xxiii. part 3. p. 763. 
f The Prostate Gland and its Enlargement in Old Age. By Decimus Hodgsox, M.D. Edin. London, 1856. 
, % “ An Account of the arrangement of the Muscular Substance in the Urinary and certain of the Generative 
Organs of the Human Body. By George Viner Ellis,” Med.-Chir. Trans, vol. xxxix. 
